Two fighter jets, armed with attack missiles, arrived in El Arish early Monday morning to assist in the effort to track down the fugitive terrorists responsible for the killing of 16 Egyptian soldiers on the border with Israel, a high-ranking security official in northern Sinai told the Egyptian news site Al Masrawi. The source added that more military aircraft were on their way.

He also said that within 48 hours, large military reinforcements would arrive in Sinai — a special measure coordinated with Israel in order to help track down the terrorists in Sinai’s rough terrain.

The Sinai has seen a surge of violence since Hosni Mubarak’s ouster last year, but Sunday’s attack was the worst in several years.